Abstract

The degeneration Of the macronucleus at every conjugation and the development of a new macronucleus from a product are two central facts in the cytological history of ciliates wherever conjugation has been studied, The precise nature of the "degeneration" of the old macronucleus, however, is unknown and vague terms like disorganization, disintegration, decomposition and final absorption have been applied to the changes occurring in it. Previous studies were directed to an analysis or some of these changes (Seshachar, '50; Seshachar and Dass, '51, '53). This paper sets out some interesting phenomena in the macronucleus of Chilodonella uncinatus during and after conjugation. An analysis of the nuclear apparatus of this ciliate by cytochemicaI methods was made some years ago (Seshaehar, '50) but a study of the changes taking place in the degenerating. macronucleus was not made. It nows appears possible to throw some light on the phenomena associated with the "degeneration" of the micronucleus in Chilodonella and its final absorption in the cytoplasm